The present invention relates generally to stripline to coaxial transitions, and more particularly, to an orthogonal stripline to coaxial transition between opposite sides of a stripline board.
Stripline to coaxial transitions are required quite often in radar seekers antennas. The antenna usually contains a hybrid of different transmission media such as waveguide and suspended air stripline, and stripline. Once the microwave energy is collected from the antenna it must be channeled to a receiver. It is this transition that must couple electromagnetic energy smoothly from the stripline medium to the coaxial medium with minimal energy loss.
The assignee of the present invention has developed a bonded stripline circuit for use in a radar seeker that requires electrical access to both sides of the circuit. It is desired that this access is achieved by means of an orthogonal coaxial connection. This can be achieved in a number of ways, however the existing state of the art has some disadvantages. Prior art coupling mechanisms employ techniques such as cutting and removing portions of the board which are labor intensive and time consuming, or use techniques that require detailed assembly.
One prior art orthogonal launch transition is fabricated such that center coax pins are first soldered to each conductor trace, and then two stripline boards are bonded together. This process is particularly difficult when orthogonal launch connections are required from both sides of the stripline boards. Movement of the pins during bonding is likely and damage to the pins is very likely. Using this approach it is very difficult to mechanically position the pins accurately, and the performance is sensitive to misalignment errors. This problem is enhanced when the diameter of the pin (i.e. the center conductor of the coax) is small, such is the case for the above-mentioned application where pin diameters are 15 thousandths of an inch.
Another prior art orthogonal launch transition is fabricated such that the stripline boards are first bonded, then the center pins are soldered. This solution requires the removal of a small portion of the stripline board below the conductive trace. The removed section must be large enough to accommodate the head of the pin and large enough to allow room to solder the head of the pin to the conductor trace. This approach is labor intensive and difficult since the removed section of the stripline board must be plugged after soldering. This also disrupts the mechanical and electrical integrity at the transition, since the plugs must be attached to the stripline board by means of conductive tape, for example. This makes RF performance difficult to repeat, especially at higher RF frequencies.
Accordingly, it is an objective of the present invention to provide for an improved orthogonal stripline to coaxial transition between opposite sides of a stripline board.